using System;
/*
 * Copyright 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace iTextSharp.text.pdf.qrcode {

    /**
     * @author satorux@google.com (Satoru Takabayashi) - creator
     * @author dswitkin@google.com (Daniel Switkin) - ported from C++
     */
    public sealed class MatrixUtil {

        private MatrixUtil() {
            // do nothing
        }

        private static readonly int[][] POSITION_DETECTION_PATTERN =  {
      new int[]{1, 1, 1, 1, 1, 1, 1},
      new int[]{1, 0, 0, 0, 0, 0, 1},
      new int[]{1, 0, 1, 1, 1, 0, 1},
      new int[]{1, 0, 1, 1, 1, 0, 1},
      new int[]{1, 0, 1, 1, 1, 0, 1},
      new int[]{1, 0, 0, 0, 0, 0, 1},
      new int[]{1, 1, 1, 1, 1, 1, 1}
  };

        private static readonly int[][] HORIZONTAL_SEPARATION_PATTERN = {
      new int[]{0, 0, 0, 0, 0, 0, 0, 0}
  };

        private static readonly int[][] VERTICAL_SEPARATION_PATTERN = {
      new int[]{0}, new int[]{0}, new int[]{0}, new int[]{0}, new int[]{0}, new int[]{0}, new int[]{0}
  };

        private static readonly int[][] POSITION_ADJUSTMENT_PATTERN = {
      new int[]{1, 1, 1, 1, 1},
      new int[]{1, 0, 0, 0, 1},
      new int[]{1, 0, 1, 0, 1},
      new int[]{1, 0, 0, 0, 1},
      new int[]{1, 1, 1, 1, 1}
  };

        // From Appendix E. Table 1, JIS0510X:2004 (p 71). The table was double-checked by komatsu.
        private static readonly int[][] POSITION_ADJUSTMENT_PATTERN_COORDINATE_TABLE = {
      new int[]{-1, -1, -1, -1,  -1,  -1,  -1},  // Version 1
      new int[]{ 6, 18, -1, -1,  -1,  -1,  -1},  // Version 2
      new int[]{ 6, 22, -1, -1,  -1,  -1,  -1},  // Version 3
      new int[]{ 6, 26, -1, -1,  -1,  -1,  -1},  // Version 4
      new int[]{ 6, 30, -1, -1,  -1,  -1,  -1},  // Version 5
      new int[]{ 6, 34, -1, -1,  -1,  -1,  -1},  // Version 6
      new int[]{ 6, 22, 38, -1,  -1,  -1,  -1},  // Version 7
      new int[]{ 6, 24, 42, -1,  -1,  -1,  -1},  // Version 8
      new int[]{ 6, 26, 46, -1,  -1,  -1,  -1},  // Version 9
      new int[]{ 6, 28, 50, -1,  -1,  -1,  -1},  // Version 10
      new int[]{ 6, 30, 54, -1,  -1,  -1,  -1},  // Version 11
      new int[]{ 6, 32, 58, -1,  -1,  -1,  -1},  // Version 12
      new int[]{ 6, 34, 62, -1,  -1,  -1,  -1},  // Version 13
      new int[]{ 6, 26, 46, 66,  -1,  -1,  -1},  // Version 14
      new int[]{ 6, 26, 48, 70,  -1,  -1,  -1},  // Version 15
      new int[]{ 6, 26, 50, 74,  -1,  -1,  -1},  // Version 16
      new int[]{ 6, 30, 54, 78,  -1,  -1,  -1},  // Version 17
      new int[]{ 6, 30, 56, 82,  -1,  -1,  -1},  // Version 18
      new int[]{ 6, 30, 58, 86,  -1,  -1,  -1},  // Version 19
      new int[]{ 6, 34, 62, 90,  -1,  -1,  -1},  // Version 20
      new int[]{ 6, 28, 50, 72,  94,  -1,  -1},  // Version 21
      new int[]{ 6, 26, 50, 74,  98,  -1,  -1},  // Version 22
      new int[]{ 6, 30, 54, 78, 102,  -1,  -1},  // Version 23
      new int[]{ 6, 28, 54, 80, 106,  -1,  -1},  // Version 24
      new int[]{ 6, 32, 58, 84, 110,  -1,  -1},  // Version 25
      new int[]{ 6, 30, 58, 86, 114,  -1,  -1},  // Version 26
      new int[]{ 6, 34, 62, 90, 118,  -1,  -1},  // Version 27
      new int[]{ 6, 26, 50, 74,  98, 122,  -1},  // Version 28
      new int[]{ 6, 30, 54, 78, 102, 126,  -1},  // Version 29
      new int[]{ 6, 26, 52, 78, 104, 130,  -1},  // Version 30
      new int[]{ 6, 30, 56, 82, 108, 134,  -1},  // Version 31
      new int[]{ 6, 34, 60, 86, 112, 138,  -1},  // Version 32
      new int[]{ 6, 30, 58, 86, 114, 142,  -1},  // Version 33
      new int[]{ 6, 34, 62, 90, 118, 146,  -1},  // Version 34
      new int[]{ 6, 30, 54, 78, 102, 126, 150},  // Version 35
      new int[]{ 6, 24, 50, 76, 102, 128, 154},  // Version 36
      new int[]{ 6, 28, 54, 80, 106, 132, 158},  // Version 37
      new int[]{ 6, 32, 58, 84, 110, 136, 162},  // Version 38
      new int[]{ 6, 26, 54, 82, 110, 138, 166},  // Version 39
      new int[]{ 6, 30, 58, 86, 114, 142, 170}   // Version 40
  };

        // Type info cells at the left top corner.
        private static readonly int[][] TYPE_INFO_COORDINATES = {
      new int[]{8, 0},
      new int[]{8, 1},
      new int[]{8, 2},
      new int[]{8, 3},
      new int[]{8, 4},
      new int[]{8, 5},
      new int[]{8, 7},
      new int[]{8, 8},
      new int[]{7, 8},
      new int[]{5, 8},
      new int[]{4, 8},
      new int[]{3, 8},
      new int[]{2, 8},
      new int[]{1, 8},
      new int[]{0, 8}
  };

        // From Appendix D in JISX0510:2004 (p. 67)
        private const int VERSION_INFO_POLY = 0x1f25;  // 1 1111 0010 0101

        // From Appendix C in JISX0510:2004 (p.65).
        private const int TYPE_INFO_POLY = 0x537;
        private const int TYPE_INFO_MASK_PATTERN = 0x5412;

        // Set all cells to -1.  -1 means that the cell is empty (not set yet).
        //
        // JAVAPORT: We shouldn't need to do this at all. The code should be rewritten to begin encoding
        // with the ByteMatrix initialized all to zero.
        public static void ClearMatrix(ByteMatrix matrix) {
            matrix.Clear((sbyte)-1);
        }

        // Build 2D matrix of QR Code from "dataBits" with "ecLevel", "version" and "getMaskPattern". On
        // success, store the result in "matrix" and return true.
        public static void BuildMatrix(BitVector dataBits, ErrorCorrectionLevel ecLevel, int version,
            int maskPattern, ByteMatrix matrix) {
            ClearMatrix(matrix);
            EmbedBasicPatterns(version, matrix);
            // Type information appear with any version.
            EmbedTypeInfo(ecLevel, maskPattern, matrix);
            // Version info appear if version >= 7.
            MaybeEmbedVersionInfo(version, matrix);
            // Data should be embedded at end.
            EmbedDataBits(dataBits, maskPattern, matrix);
        }

        // Embed basic patterns. On success, modify the matrix and return true.
        // The basic patterns are:
        // - Position detection patterns
        // - Timing patterns
        // - Dark dot at the left bottom corner
        // - Position adjustment patterns, if need be
        public static void EmbedBasicPatterns(int version, ByteMatrix matrix) {
            // Let's get started with embedding big squares at corners.
            EmbedPositionDetectionPatternsAndSeparators(matrix);
            // Then, embed the dark dot at the left bottom corner.
            EmbedDarkDotAtLeftBottomCorner(matrix);

            // Position adjustment patterns appear if version >= 2.
            MaybeEmbedPositionAdjustmentPatterns(version, matrix);
            // Timing patterns should be embedded after position adj. patterns.
            EmbedTimingPatterns(matrix);
        }

        // Embed type information. On success, modify the matrix.
        public static void EmbedTypeInfo(ErrorCorrectionLevel ecLevel, int maskPattern, ByteMatrix matrix) {
            BitVector typeInfoBits = new BitVector();
            MakeTypeInfoBits(ecLevel, maskPattern, typeInfoBits);

            for (int i = 0; i < typeInfoBits.Size(); ++i) {
                // Place bits in LSB to MSB order.  LSB (least significant bit) is the last value in
                // "typeInfoBits".
                int bit = typeInfoBits.At(typeInfoBits.Size() - 1 - i);

                // Type info bits at the left top corner. See 8.9 of JISX0510:2004 (p.46).
                int x1 = TYPE_INFO_COORDINATES[i][0];
                int y1 = TYPE_INFO_COORDINATES[i][1];
                matrix.Set(x1, y1, bit);

                if (i < 8) {
                    // Right top corner.
                    int x2 = matrix.GetWidth() - i - 1;
                    int y2 = 8;
                    matrix.Set(x2, y2, bit);
                }
                else {
                    // Left bottom corner.
                    int x2 = 8;
                    int y2 = matrix.GetHeight() - 7 + (i - 8);
                    matrix.Set(x2, y2, bit);
                }
            }
        }

        // Embed version information if need be. On success, modify the matrix and return true.
        // See 8.10 of JISX0510:2004 (p.47) for how to embed version information.
        public static void MaybeEmbedVersionInfo(int version, ByteMatrix matrix) {
            if (version < 7) {  // Version info is necessary if version >= 7.
                return;  // Don't need version info.
            }
            BitVector versionInfoBits = new BitVector();
            MakeVersionInfoBits(version, versionInfoBits);

            int bitIndex = 6 * 3 - 1;  // It will decrease from 17 to 0.
            for (int i = 0; i < 6; ++i) {
                for (int j = 0; j < 3; ++j) {
                    // Place bits in LSB (least significant bit) to MSB order.
                    int bit = versionInfoBits.At(bitIndex);
                    bitIndex--;
                    // Left bottom corner.
                    matrix.Set(i, matrix.GetHeight() - 11 + j, bit);
                    // Right bottom corner.
                    matrix.Set(matrix.GetHeight() - 11 + j, i, bit);
                }
            }
        }

        // Embed "dataBits" using "getMaskPattern". On success, modify the matrix and return true.
        // For debugging purposes, it skips masking process if "getMaskPattern" is -1.
        // See 8.7 of JISX0510:2004 (p.38) for how to embed data bits.
        public static void EmbedDataBits(BitVector dataBits, int maskPattern, ByteMatrix matrix) {
            int bitIndex = 0;
            int direction = -1;
            // Start from the right bottom cell.
            int x = matrix.GetWidth() - 1;
            int y = matrix.GetHeight() - 1;
            while (x > 0) {
                // Skip the vertical timing pattern.
                if (x == 6) {
                    x -= 1;
                }
                while (y >= 0 && y < matrix.GetHeight()) {
                    for (int i = 0; i < 2; ++i) {
                        int xx = x - i;
                        // Skip the cell if it's not empty.
                        if (!IsEmpty(matrix.Get(xx, y))) {
                            continue;
                        }
                        int bit;
                        if (bitIndex < dataBits.Size()) {
                            bit = dataBits.At(bitIndex);
                            ++bitIndex;
                        }
                        else {
                            // Padding bit. If there is no bit left, we'll fill the left cells with 0, as described
                            // in 8.4.9 of JISX0510:2004 (p. 24).
                            bit = 0;
                        }

                        // Skip masking if mask_pattern is -1.
                        if (maskPattern != -1) {
                            if (MaskUtil.GetDataMaskBit(maskPattern, xx, y)) {
                                bit ^= 0x1;
                            }
                        }
                        matrix.Set(xx, y, bit);
                    }
                    y += direction;
                }
                direction = -direction;  // Reverse the direction.
                y += direction;
                x -= 2;  // Move to the left.
            }
            // All bits should be consumed.
            if (bitIndex != dataBits.Size()) {
                throw new WriterException("Not all bits consumed: " + bitIndex + '/' + dataBits.Size());
            }
        }

        // Return the position of the most significant bit set (to one) in the "value". The most
        // significant bit is position 32. If there is no bit set, return 0. Examples:
        // - FindMSBSet(0) => 0
        // - FindMSBSet(1) => 1
        // - FindMSBSet(255) => 8
        public static int FindMSBSet(int value) {
            uint val = (uint)value;
            int numDigits = 0;
            while (val != 0) {
                val >>= 1;
                ++numDigits;
            }
            return numDigits;
        }

        // Calculate BCH (Bose-Chaudhuri-Hocquenghem) code for "value" using polynomial "poly". The BCH
        // code is used for encoding type information and version information.
        // Example: Calculation of version information of 7.
        // F(x) is created from 7.
        //   - 7 = 000111 in 6 bits
        //   - F(x) = x^2 + x^2 + x^1
        // G(x) is given by the standard (p. 67)
        //   - G(x) = x^12 + x^11 + x^10 + x^9 + x^8 + x^5 + x^2 + 1
        // Multiply F(x) by x^(18 - 6)
        //   - f'(x) = F(x) * x^(18 - 6)
        //   - f'(x) = x^14 + x^13 + x^12
        // Calculate the remainder of f'(x) / G(x)
        //         x^2
        //         __________________________________________________
        //   G(x) )x^14 + x^13 + x^12
        //         x^14 + x^13 + x^12 + x^11 + x^10 + x^7 + x^4 + x^2
        //         --------------------------------------------------
        //                              x^11 + x^10 + x^7 + x^4 + x^2
        //
        // The remainder is x^11 + x^10 + x^7 + x^4 + x^2
        // Encode it in binary: 110010010100
        // The return value is 0xc94 (1100 1001 0100)
        //
        // Since all coefficients in the polynomials are 1 or 0, we can do the calculation by bit
        // operations. We don't care if cofficients are positive or negative.
        public static int CalculateBCHCode(int value, int poly) {
            // If poly is "1 1111 0010 0101" (version info poly), msbSetInPoly is 13. We'll subtract 1
            // from 13 to make it 12.
            int msbSetInPoly = FindMSBSet(poly);
            value <<= msbSetInPoly - 1;
            // Do the division business using exclusive-or operations.
            while (FindMSBSet(value) >= msbSetInPoly) {
                value ^= poly << (FindMSBSet(value) - msbSetInPoly);
            }
            // Now the "value" is the remainder (i.e. the BCH code)
            return value;
        }

        // Make bit vector of type information. On success, store the result in "bits" and return true.
        // Encode error correction level and mask pattern. See 8.9 of
        // JISX0510:2004 (p.45) for details.
        public static void MakeTypeInfoBits(ErrorCorrectionLevel ecLevel, int maskPattern, BitVector bits) {
            if (!QRCode.IsValidMaskPattern(maskPattern)) {
                throw new WriterException("Invalid mask pattern");
            }
            int typeInfo = (ecLevel.GetBits() << 3) | maskPattern;
            bits.AppendBits(typeInfo, 5);

            int bchCode = CalculateBCHCode(typeInfo, TYPE_INFO_POLY);
            bits.AppendBits(bchCode, 10);

            BitVector maskBits = new BitVector();
            maskBits.AppendBits(TYPE_INFO_MASK_PATTERN, 15);
            bits.Xor(maskBits);

            if (bits.Size() != 15) {  // Just in case.
                throw new WriterException("should not happen but we got: " + bits.Size());
            }
        }

        // Make bit vector of version information. On success, store the result in "bits" and return true.
        // See 8.10 of JISX0510:2004 (p.45) for details.
        public static void MakeVersionInfoBits(int version, BitVector bits) {
            bits.AppendBits(version, 6);
            int bchCode = CalculateBCHCode(version, VERSION_INFO_POLY);
            bits.AppendBits(bchCode, 12);

            if (bits.Size() != 18) {  // Just in case.
                throw new WriterException("should not happen but we got: " + bits.Size());
            }
        }

        // Check if "value" is empty.
        private static bool IsEmpty(int value) {
            return value == -1;
        }

        // Check if "value" is valid.
        private static bool IsValidValue(int value) {
            return (value == -1 ||  // Empty.
                value == 0 ||  // Light (white).
                value == 1);  // Dark (black).
        }

        private static void EmbedTimingPatterns(ByteMatrix matrix) {
            // -8 is for skipping position detection patterns (size 7), and two horizontal/vertical
            // separation patterns (size 1). Thus, 8 = 7 + 1.
            for (int i = 8; i < matrix.GetWidth() - 8; ++i) {
                int bit = (i + 1) % 2;
                // Horizontal line.
                if (!IsValidValue(matrix.Get(i, 6))) {
                    throw new WriterException();
                }
                if (IsEmpty(matrix.Get(i, 6))) {
                    matrix.Set(i, 6, bit);
                }
                // Vertical line.
                if (!IsValidValue(matrix.Get(6, i))) {
                    throw new WriterException();
                }
                if (IsEmpty(matrix.Get(6, i))) {
                    matrix.Set(6, i, bit);
                }
            }
        }

        // Embed the lonely dark dot at left bottom corner. JISX0510:2004 (p.46)
        private static void EmbedDarkDotAtLeftBottomCorner(ByteMatrix matrix) {
            if (matrix.Get(8, matrix.GetHeight() - 8) == 0) {
                throw new WriterException();
            }
            matrix.Set(8, matrix.GetHeight() - 8, 1);
        }

        private static void EmbedHorizontalSeparationPattern(int xStart, int yStart,
            ByteMatrix matrix) {
            // We know the width and height.
            if (HORIZONTAL_SEPARATION_PATTERN[0].Length != 8 || HORIZONTAL_SEPARATION_PATTERN.GetLength(0) != 1) {
                throw new WriterException("Bad horizontal separation pattern");
            }
            for (int x = 0; x < 8; ++x) {
                if (!IsEmpty(matrix.Get(xStart + x, yStart))) {
                    throw new WriterException();
                }
                matrix.Set(xStart + x, yStart, HORIZONTAL_SEPARATION_PATTERN[0][x]);
            }
        }

        private static void EmbedVerticalSeparationPattern(int xStart, int yStart,
            ByteMatrix matrix) {
            // We know the width and height.
            if (VERTICAL_SEPARATION_PATTERN[0].Length != 1 || VERTICAL_SEPARATION_PATTERN.GetLength(0) != 7) {
                throw new WriterException("Bad vertical separation pattern");
            }
            for (int y = 0; y < 7; ++y) {
                if (!IsEmpty(matrix.Get(xStart, yStart + y))) {
                    throw new WriterException();
                }
                matrix.Set(xStart, yStart + y, VERTICAL_SEPARATION_PATTERN[y][0]);
            }
        }

        // Note that we cannot unify the function with EmbedPositionDetectionPattern() despite they are
        // almost identical, since we cannot write a function that takes 2D arrays in different sizes in
        // C/C++. We should live with the fact.
        private static void EmbedPositionAdjustmentPattern(int xStart, int yStart,
            ByteMatrix matrix) {
            // We know the width and height.
            if (POSITION_ADJUSTMENT_PATTERN[0].Length != 5 || POSITION_ADJUSTMENT_PATTERN.GetLength(0) != 5) {
                throw new WriterException("Bad position adjustment");
            }
            for (int y = 0; y < 5; ++y) {
                for (int x = 0; x < 5; ++x) {
                    if (!IsEmpty(matrix.Get(xStart + x, yStart + y))) {
                        throw new WriterException();
                    }
                    matrix.Set(xStart + x, yStart + y, POSITION_ADJUSTMENT_PATTERN[y][x]);
                }
            }
        }

        private static void EmbedPositionDetectionPattern(int xStart, int yStart,
            ByteMatrix matrix) {
            // We know the width and height.
            if (POSITION_DETECTION_PATTERN[0].Length != 7 || POSITION_DETECTION_PATTERN.GetLength(0) != 7) {
                throw new WriterException("Bad position detection pattern");
            }
            for (int y = 0; y < 7; ++y) {
                for (int x = 0; x < 7; ++x) {
                    if (!IsEmpty(matrix.Get(xStart + x, yStart + y))) {
                        throw new WriterException();
                    }
                    matrix.Set(xStart + x, yStart + y, POSITION_DETECTION_PATTERN[y][x]);
                }
            }
        }

        // Embed position detection patterns and surrounding vertical/horizontal separators.
        private static void EmbedPositionDetectionPatternsAndSeparators(ByteMatrix matrix) {
            // Embed three big squares at corners.
            int pdpWidth = POSITION_DETECTION_PATTERN[0].Length;
            // Left top corner.
            EmbedPositionDetectionPattern(0, 0, matrix);
            // Right top corner.
            EmbedPositionDetectionPattern(matrix.GetWidth() - pdpWidth, 0, matrix);
            // Left bottom corner.
            EmbedPositionDetectionPattern(0, matrix.GetWidth() - pdpWidth, matrix);

            // Embed horizontal separation patterns around the squares.
            int hspWidth = HORIZONTAL_SEPARATION_PATTERN[0].Length;
            // Left top corner.
            EmbedHorizontalSeparationPattern(0, hspWidth - 1, matrix);
            // Right top corner.
            EmbedHorizontalSeparationPattern(matrix.GetWidth() - hspWidth,
                hspWidth - 1, matrix);
            // Left bottom corner.
            EmbedHorizontalSeparationPattern(0, matrix.GetWidth() - hspWidth, matrix);

            // Embed vertical separation patterns around the squares.
            int vspSize = VERTICAL_SEPARATION_PATTERN.Length;
            // Left top corner.
            EmbedVerticalSeparationPattern(vspSize, 0, matrix);
            // Right top corner.
            EmbedVerticalSeparationPattern(matrix.GetHeight() - vspSize - 1, 0, matrix);
            // Left bottom corner.
            EmbedVerticalSeparationPattern(vspSize, matrix.GetHeight() - vspSize,
                matrix);
        }

        // Embed position adjustment patterns if need be.
        private static void MaybeEmbedPositionAdjustmentPatterns(int version, ByteMatrix matrix) {
            if (version < 2) {  // The patterns appear if version >= 2
                return;
            }
            int index = version - 1;
            int[] coordinates = POSITION_ADJUSTMENT_PATTERN_COORDINATE_TABLE[index];
            int numCoordinates = POSITION_ADJUSTMENT_PATTERN_COORDINATE_TABLE[index].Length;
            for (int i = 0; i < numCoordinates; ++i) {
                for (int j = 0; j < numCoordinates; ++j) {
                    int y = coordinates[i];
                    int x = coordinates[j];
                    if (x == -1 || y == -1) {
                        continue;
                    }
                    // If the cell is unset, we embed the position adjustment pattern here.
                    if (IsEmpty(matrix.Get(x, y))) {
                        // -2 is necessary since the x/y coordinates point to the center of the pattern, not the
                        // left top corner.
                        EmbedPositionAdjustmentPattern(x - 2, y - 2, matrix);
                    }
                }
            }
        }
    }
}